In a sauce pan on medium heat, melt butter and add the flour to make roux.
Continue to stir the roux till it darkens and not burnt. We are making a dark roux. Looking for a milk chocolate colour.
Add curry powder, garam malasa and cayenne pepper and cook for about 1 minute to bring out the fragrance.
Add the onions, carrots, tomatoes, potatoes and garlic. Sautee for a few mins.
Add the stock or water to the pot and bring to a boil.
Simmer for 15-20 minutes. Stir occasionally to make sure the bottom doesn’t stick.
If sauce is getting too thick, add more stock or water to the desired consistency. Looking for a nice consistency, more on thicker side. The potatoes breaking down will add to the thicker consistency of the sauce.
Season with salt, pepper and sugar to taste.